Burner unit

ABSTRACT

Example embodiments relate to a burner unit for combusting an air-fuel mixture. The burner unit includes an air supply dome having recesses which have a larger width on an inside of the air supply dome than on an outside.

FIELD OF DISCLOSURE

The present disclosure relates to a burner unit for combusting anair-fuel mixture.

BACKGROUND

The burner unit is, for example, part of a heater for heating air or aliquid, e.g. water. The fuel is, for example, diesel, gasoline or acombustible gas (e.g. propane).

DE 295 11 384 U1 describes a burner unit having an outer tube and aninner tube. The inner tube is located within the outer tube and allowscombustion air to be supplied via slots. The fuel is introduced into theouter tube. The resultant mixture of air and fuel is combusted in aflame tube. The structure of a combustion chamber is further taught inDE 633 304, DE 44 42 425 B4, DE 44 47 986 B4, DE 195 29 994 A1 or DE 102013 109 184 A1.

For combustion to be as complete and as low in pollutants as possible,it is required that the air and fuel be mixed as well as possible.

It is therefore the object of the invention to propose a burner unitwhich allows the air-fuel mixture to be combusted as well as possible.

SUMMARY

The present disclosure achieves the object by a burner unit forcombusting an air-fuel mixture, having a combustion space, a combustionair guide dome and a fuel inlet, wherein the combustion air guide domeis located in the combustion space and has recesses, wherein the fuelinlet opens into the combustion space, and wherein the recesses have alarger width on an inside of the combustion air guide dome than on anoutside of the air supply dome.

The recesses in the combustion dome, through which the (combustion) airpasses from the interior of the dome into the combustion space, do nothave a constant width but narrow from the inside to the outside. Theview in each case here is in a plane perpendicular to a longitudinalaxis of the dome and/or the burner unit. The dome may alternatively alsobe referred to as an inner tube or inner cylinder. Furthermore, thefuel, that is, e.g. diesel, enters the combustion space via a fuelinlet. It has been found that the narrowing of the recesses improvesmixing. This results, for example, in a more homogeneous velocitydistribution in the combustion space. Furthermore, pressure losses canbe avoided, for example.

The recesses are, for example, in the form of slots along thelongitudinal axis. The air enters the interior of the dome via a fan,for example, and from there into the combustion space around the airsupply dome. In one configuration, the burner unit is part of a heatingsystem.

One configuration consists in that the recesses taper from the inside tothe outside. For example, the side walls of the recesses have an evenprofile with a constant slope.

One configuration provides that the recesses are configured such thatthey produce a nozzle effect for air directed out of the combustion airguide dome.

One configuration consists in that the recesses have a substantiallyconstant profile along a longitudinal axis of the air supply dome. Forexample, the recesses are axially oriented slots. An alternativeconfiguration provides that the recesses change their shape along alongitudinal axis of the air supply dome. The combustion air guide domemay be closed or open on the face side.

In particular, the longitudinal axis of the combustion air guide dome isperpendicular to the direction in which the recesses become narrowerfrom the inside to the outside.

One configuration consists in that the combustion air guide dome has asubstantially circular cylindrical shape. The combustion air guide domemay be closed or open on the face side.

One configuration provides that the recesses have different heightsalong a longitudinal axis of the air supply dome. In this configuration,the recesses have different lengths or extents in the axial direction.An alternative configuration consists in that the recesses have a commonheight along a longitudinal axis of the air supply dome. In thisconfiguration, the recesses have a common or equal axial extent alongthe longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

In detail, there is a multitude of options for configuring and furtherdeveloping the burner unit according to the invention. In this regard,reference is made, for one thing, to the claims dependent on claim 1and, for another thing, to the following description of exemplaryembodiments in conjunction with the drawings, in which:

FIG. 1 shows a section taken through a schematic representation of theburner unit along the longitudinal axis; and

FIG. 2 shows a section taken through the burner unit perpendicular tothe longitudinal axis.

DETAILED DESCRIPTION

FIG. 1 schematically shows a burner unit 1, which is for example part ofa heating system. A mixture of a fuel, e.g. gas or diesel, andcombustion air is combusted in the burner space 2. Good mixing isrequired for a combustion which is as effective as possible and whichalso produces as few pollutants as possible. The combustion air entersthe combustion space 2 via the recesses 4 in the combustion air guidedome 3. The recesses 4 are in the form of slots here, which originatefrom the inner face side of the combustion air guide dome 3 and extendalong the longitudinal axis 6 of the burner unit 1 and here also of thecombustion air guide dome 3. The shape of the recesses 4 is thusconstant in the axial direction and the recesses 4 extend parallel toone another. In the configuration shown, the recesses 4 furthermore havea common height, that is, a common, i.e., equal, axial extent. Thecombustion air guide dome 4 is a cylinder having a circular base area.The fuel enters the combustion space 2 via a fuel inlet 5.

FIG. 2 shows a section taken through the combustion air guide dome 3along the longitudinal axis 6. The recesses 4 can be seen, which extendfrom the inside 30 to the outside 31 and become narrower from the insideto the outside. The width of the recesses 4 is thus greater on theinside 30 than on the outside 31. This results in the effect of anozzle.

LIST OF REFERENCE NUMBERS

-   -   1 burner unit    -   2 combustion space    -   3 combustion air guide dome    -   4 recess    -   5 fuel inlet    -   6 longitudinal axis of combustion air guide dome    -   30 inside of combustion air guide dome    -   31 outside of combustion air guide dome

1. A burner unit for combusting an air-fuel mixture, comprising acombustion space, a combustion air guide dome and a fuel inlet, whereinthe combustion air guide dome is located in the combustion space and hasrecesses, wherein the fuel inlet opens into the combustion space, andwherein the recesses have a larger width on an inside of the combustionair guide dome than on an outside of the combustion air guide dome. 2.The burner unit according to claim 1, wherein the recesses taper fromthe inside to the outside.
 3. The burner unit according to claim 1,wherein the recesses are configured such that they produce a nozzleeffect for air directed out of the combustion air guide dome.
 4. Theburner unit according to claim 1, wherein the recesses have a constantprofile along a longitudinal axis of the combustion air guide dome-dome.5. The burner unit according to claim 1, wherein the combustion airguide dome has a circular cylindrical shape.
 6. The burner unitaccording to claim 1, wherein the recesses have a common height along alongitudinal axis of the combustion air guide dome.